Finish incomplete sentence in docstring.

Fixes #1389

diff --git a/tornado/ioloop.py b/tornado/ioloop.py
index 3c7fb11115d520112a0707f5366b2485f787081d..f18d6985b2b9638fc4101037410a746e9d6c7f10 100644 (file)
--- a/tornado/ioloop.py
+++ b/tornado/ioloop.py
@@ -189,8 +189,8 @@ class IOLoop(Configurable):
         one.
 
         .. versionchanged:: 4.1
-           Added ``instance`` argument to control the
-
+           Added ``instance`` argument to control the fallback to
+           `IOLoop.instance()`.
         """
         current = getattr(IOLoop._current, "instance", None)
         if current is None and instance: